Apparatus for measuring viscosity



March 31, 1953 w, MILLlNGTON I 2,633,016

APPARATUS FOR MEASURING VISCOSITY Filed Aug. 29, 1947 2 SHEETS-SHEET 1 z F761. g 52 4 IN V EN TOR.

F763. 1 J01? W W Mfllz'nylon ATTORNEYS March 31, 1953 Y J w. MILLINGTON 12,633,016 APPARATUS FOR MEASURING VISCOSITY Filed Aug. 29, 1947 v 2 SHEETS-SHEET 2 .INVENTOR. Jo/ng WMlZz'n for? ATTOZNEYs Patented Mar. 31, 1953 2,633,016 APPARATUS FOR MEASURING VISCOSITY 7 John W. Millington, Beaumont, Tex., assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey Application August 29, 1947, Serial No. 771,177

2 Claims.

This invention relates to methods and apparatus for the making of physical measurements and has particular reference to the making of measurements in bore holes though, as will be evident hereafter, the various features of the invention are applicable to the making of physical measurements in general, including laboratory or industrial measurements.

In accordance with the invention liquid viscosity may be measured continuously while the recording instrument is lowered into a bore hole, or the tubing of a producing well, so as to make possible a continuous study of the conditions being encountered.

One object of the invention is the provision of improved means for making viscosity measurements, particularly at remote points, with transmission of these measurements to an observer.

This general object of the invention, together with other objects relating to features of transmission and the like, will become apparent from the following description read in conjunction with the accompanying drawings in which:

Figure 1 is a wiring diagram illustrating apparatus for the measurement of viscosity;

Figure 2 is an axial sectional view illustrating the construction of a transducer involved in viscosity measurements; and

Figure 3 is an axial sectional view illustrating the construction of a transducer for the continuous monitoring of a flowing fluid.

In order to provide a, measurement of viscosity an oscillator 52 supplies a bridge consisting of resistors 54 and 56 and the coil in each of a pair of transducers 58 and 60, each of which may be of a type which will now be described. "Figure 2 illustrates one of these transducers, for" example, the transducer 60 which receives liquid from the well. This transducer comprises housing sections 62, 64 and 66, the last of which is. provided with openings 68 while the section 64 is provided with openings for the flow of the well fluid. This fluid may consist of liquid or gas or a mixture of liquid and gas. Figure 2 illustrates thetransducer with a rounded nose such as provided if it were used alone. It will, of course, be understood that if this element is located above some lower element the rounded nose would'be replaced by a coupling provided withopenings such as 68.

To an internally directed flange 12 there is secured by silver soldering or other means providing a liquid tight connection the center of a rod 14 of nickel or other material having magnetostriction properties, i. e., subject to change of dimension with variation of a magnetic field passing through it. At its upper end the rod carries a member 16 of magnetic material having small clearance with the interiorof the section 62 which. "as well'a's the se'ction 64, is also of magnetic material such as steel. A coil 8!! surrounds the rod M as illustrated and a magnetic circuit is thus provided through the member 62, the member '64 and its internal flange 12, the upper end of the rod 14 and the member 18. Current from the bridge thus provides a varying magnetic flux which produces longitudinal'vibrationin the rod 14. To'the lower end of the rod 14 there is secured a piston 18 having slight clearance with the walls of the section 66 of, the casing. Leads 82 fromthe coils connect to the bridge.

The mechanical oscillating system consists of the rod 14, the piston 18 and the member 16. The oscillations are variably damped depending upon the nature of the fluid surrounding the piston and consequently the transducer presents in the bridge a variable impedance depending upon the nature of the bore hole fluid.

The second transducer 58 may be identical in construction except that it is not provided with openings such as 68 and 10 and contains a permanent body of fluid, such as an oil, thereby constituting a fixed impedance acting as a reference for the variations of impedance of the trans ducer 60. The unbalance of the bridge andthe direction of unbalance will be a measure of the viscosity of the fluid in the hole. 7

The output of the bridge is fed to apparatus indicated at 44 comprising an amplifier, rectifier and filter of conventional type delivering a direct potential output to control the reactance of a reactance tube circuit also of conventional type in: dicated at 46. This reactance tube circuit forms the variable reactance of a frequency modulated oscillator of conventional type indicated at 48 Such an oscillator may be of the type illustrated in the application of Alfred C. Winterhalter, Serial No. 656,803, filed March 25, 1946, now abandoned, and described also in the article Frequency Modulation of Resistance Capacity Oscillators by Maurize Artz in the Proceedings of the IRE, July 1944. The apparatus comprising the parts 44, 46 and 48 functions in conventional fashion to provide frequency modulation of a carrier which may be of audio or higher frequency. As will be evident, the output delivered through the lines 86 will consist of a carrier frequency modulated in accordance with the viscosity by reason of the degree of unbalance of the bridge effected with variation of position of the armature 16. The frequency modulated output may be transmitted to the surface in variousways. Un-f der conditions in which it is feasible to provide a transmission line the output current may be transmitted directly through such line to the surface where a suitable demodulator of conventional nature will give rise to a direct current output which may be calibrated in terms of pressure. Alternatively, sound vibrations may be set up at a frequency modulated audio frequency for trans mission as sound along a drill stem or along a supporting wire line. As a further alternative the frequency modulated output at 86 may be used to modulate an ultra high frequency wave transmitted through a drill stem or other tubing constituting a wave guide. In any case, suitable apparatus of conventional type at the surface may be used to retranslate the signal to give rise through demodulation to a direct output which will be a function of the viscosity.

It may be remarked that frequency modulation is desirable because an attempt to use amplitude modulation would give rise to difiiculties in view of variable transmission losses at different depths of operation.

' If a cable is used the direct potential supplies necessary for 'the'apparatus at the bottom of the hole'may be provided through the cable from the surface, the same cable transmitting the signals as alternating currents. When a cable is not used, or even if a cable is used, batteries may supply the apparatus at the bottom of the hole which may operate at low power levels using miniature tubes of low power consumption.

' While the foregoing apparatus is particularly applicable to measurements in a bore hole of the type indicated it will, of course, be evident that the bridge systems and their associated'apparatus may be used for similar measurements in the laboratory or in industry for control or recording or indicating purposes. In particular, the viscosity measuring system is useful in that it gives rise to an electrical output constituting a function of viscosity, which output may be used for control purposes or for control of recording or indicating apparatus of conventional types. The control which is effected, for example, may be used to modify the flow of blending constituents or the like.

There is indicated in Figure 3 a transducer of a type differing from that of Figure 2. Specifically, this is illustrated as a transducer such as might be used in a laboratory or in industrial measurements of viscosity. This transducer comprises a housing 88 of non-magnetic material provided with covers 90 and 92 and with inlet and outlet connections respectively illustrated at 94 and 90. Within the casing is a member 98 of magnetic material which, together with a plate I of magnetic materialand a cylindrical permanent magnet -I02 provides a field having a gap receiving a coil I06 wound on a core I04. A pair of coupled rods I08 and I I0 are connected to the carrier I04, the last'rod -I I0 being provided with a piston indicated at H2. The movable assembly thus provided is mounted by flexible spiders H4 and IIS for axial vibration. A flexible diaphragm I I8 segregates the fluid chamber beneath it from the upper region of the housing containing the magnetic field members and the coil. Leads I20 are provided to connect the coil I06 in a bridge such as indicated in Figure 1. As will be evident, there is in Figure 3, as in Figure 2, a vibrating system having an apparent impedance viewed from the connection I20 which depends upon the viscosity of the fiuid in thechamber surrounding the piston I'I.2. A similar transducer may be provided in another arm of the bridge for reference purposes, this reference transducer being permanently filled with a liquid of desired property. It will be evident that the moving coil type of transducer just described may be used in a bore hole as well as that illustrated in Figure 2 although in such case, due to thelhigh pressures, the diaphragm I18 would be omitted which means that the bore hole fluid would surround all of the, moving parts.

The magnetostriction transducer is thus more desirable since the bore hole fluid may be isolated from the coil.

When used in a bore hole for the determination of viscosity of a drilling mud the viscosity responsive apparatus may control a signal device to give warning when the viscosity falls outside desired limits. Whether used in a bore hole or otherwise, it is desirable that the reference transducers should be filled with a fluid having the same viscosity-temperature characteristics as the fluid to be measured so that the response of the system is to viscosity changes alone.

It will be evident from the above that the invention is applicable quite generally and accordingly it is'to be understood that it is not limited except in accordance with the following claims.

What I claim and desire to protect by Letters Patent is:

1. Apparatus for the measurement of viscosity comprising a housing, a driving coil contained within the housing, a rod of magneto-strictive material disposed within the coil and having a portion projecting beyond the coil, said rod being anchored intermediate its ends to said housing and sealed against liquid enterin the portion of the housing containing the coil, the free end of said projecting portion of said rod being provided with a piston, and the housing including a portion surrounding said piston for presenting the test liquid therebetween, said rod being mounted to be oscillated by current through said coil, an impedance bridge including said coil in one of its arms, means for energizing said bridge with alternating current, and means for measuring the unbalance of said bridge as a measurement of damping action on oscillations of said element by the viscosity of the liquid.

2. Apparatus for the measurement of viscosity comprising a tubular housing, a driving coil contained within .the housing, a rod of magnetostri-ctive material disposed within the coil and having a portion projecting beyond the coil, said rod being anchored intermediate its ends to said housing and sealed against liquid entering the portion of the housing containing the coil, the free end of said projecting portion of said rod being provided with a piston, and the housing including an extension having a portion surrounding said piston for presenting a film of the test liquid therebetween,said rod being mounted to be oscillated by current through said coil, an impedance bridge including said coil in one of its arms, means for energizing said bridge with alternating current, and means for measuring the unbalance of said bridge as a measurement of damping action on oscillations of said element by the'visccsity of the liquid.

JOHN W. MILLINGTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,832,901 Harrison Nov. 24, 1931 2,142,854 La Pierre Jan. 3, 1939 2,315,127 Mounce Mar. 30, 1943 2,340,507 Bjork Feb. 1, 1944 2,340,992 Siegel Feb. 3, 1944 2,396,420 Hayward, et al. Mar. 12, 1946 2,412,575 Frosch Dec. 17, 1946 2,422,806 Silverman et al. June 24, 1947 2,425,868 Dillon Aug. 19, 1947 

